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      1 grammar t018llstar;
      2 
      3 options {
      4     language = JavaScript;
      5 }
      6 
      7 @members {
      8 this.olog = [];
      9 this.output = function(msg) {
     10     this.olog.push(msg);
     11 };
     12 }
     13 
     14 program
     15     :   declaration+
     16     ;
     17 
     18 /** In this rule, the functionHeader left prefix on the last two
     19  *  alternatives is not LL(k) for a fixed k.  However, it is
     20  *  LL(*).  The LL(*) algorithm simply scans ahead until it sees
     21  *  either the ';' or the '{' of the block and then it picks
     22  *  the appropriate alternative.  Lookhead can be arbitrarily
     23  *  long in theory, but is <=10 in most cases.  Works great.
     24  *  Use ANTLRWorks to see the lookahead use (step by Location)
     25  *  and look for blue tokens in the input window pane. :)
     26  */
     27 declaration
     28     :   variable
     29     |   functionHeader ';'
     30 	{this.output($functionHeader.name+" is a declaration");}
     31     |   functionHeader block
     32 	{this.output($functionHeader.name+" is a definition");}
     33     ;
     34 
     35 variable
     36     :   type declarator ';'
     37     ;
     38 
     39 declarator
     40     :   ID 
     41     ;
     42 
     43 functionHeader returns [name]
     44     :   type ID '(' ( formalParameter ( ',' formalParameter )* )? ')'
     45 	{$name = $ID.text}
     46     ;
     47 
     48 formalParameter
     49     :   type declarator        
     50     ;
     51 
     52 type
     53     :   'int'   
     54     |   'char'  
     55     |   'void'
     56     |   ID        
     57     ;
     58 
     59 block
     60     :   '{'
     61             variable*
     62             stat*
     63         '}'
     64     ;
     65 
     66 stat: forStat
     67     | expr ';'      
     68     | block
     69     | assignStat ';'
     70     | ';'
     71     ;
     72 
     73 forStat
     74     :   'for' '(' assignStat ';' expr ';' assignStat ')' block        
     75     ;
     76 
     77 assignStat
     78     :   ID '=' expr        
     79     ;
     80 
     81 expr:   condExpr
     82     ;
     83 
     84 condExpr
     85     :   aexpr ( ('==' | '<') aexpr )?
     86     ;
     87 
     88 aexpr
     89     :   atom ( '+' atom )*
     90     ;
     91 
     92 atom
     93     : ID      
     94     | INT      
     95     | '(' expr ')'
     96     ; 
     97 
     98 ID  :   ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*
     99     ;
    100 
    101 INT :	('0'..'9')+
    102     ;
    103 
    104 WS  :   (   ' '
    105         |   '\t'
    106         |   '\r'
    107         |   '\n'
    108         )+
    109         {$channel=HIDDEN}
    110     ;    
    111